This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to Appln. No. 100 06 167.2 filed in Germany on Feb. 11, 2000; the entire content of which is hereby incorporated by reference.
The invention is based on a power breaker as claimed in the precharacterizing clause of claim 1.
The two laid-open specifications DE 196 13 568 A1 and DE 196 13 569 A1 disclose a power breaker which can be used in an electrical high-voltage network, in particular as a generator switch as well. This power breaker has a cylindrical arcing chamber which is filled with SF6 gas as a quenching and insulating medium. This arcing chamber has a power current path in which the erosion-resistant consumable contacts are located, which are connected by a bridging contact in the connected state and, furthermore, it has a separate rated current path, in which the rated current contacts are fitted. The contacts in the two current paths are operated via a lever linkage from a drive, with the lever linkage being designed such that the rated current contacts always move at a slower speed than the bridging contact. During disconnection, the rated current contacts and the bridging contact move apart jointly, but the rated current path is always interrupted first, following which the current which is to be disconnected commutates onto the power current path. The power current path then continues to carry the current until it is definitively disconnected. Power breakers such as this generally require a comparatively large amount of drive energy. At the end of the disconnection travel of the contacts, the kinetic energy of the moving parts, in particular that of the rated current contacts which have a comparatively high mass, must be damped out in a complex manner.
The invention achieves the object of providing a power breaker which can be produced cost-effectively.
The advantages achieved by the invention are that the power breaker requires less drive energy, and can thus be equipped with a weaker, and thus more cost-effective, drive.
The power breaker is provided with at least one arcing chamber which is filled with an insulating medium, in particular SF6 gas, is rotationally symmetrical, and extends along a longitudinal axis. The arcing chamber has a power current path with a central contact pin and a separate rated current path, which is provided with rated current contacts. The arcing chamber is operated by a drive linkage which moves the contact pin and the rated current contacts. The drive linkage is designed such that, at the start of the disconnection process, the contact pin remains in a first dead point position until the rated current path is interrupted. The contact pin can then be moved in the disconnection direction at a considerably higher speed than the rated current contacts. The rated current contacts run into a second dead point position toward the end of their disconnection travel. The contact pin does not reach its disconnected position until after the rated current contacts have ended their disconnection movement. At the start of the connection process, the rated current contacts remain in this second dead point position until the pre-arcing of the switch-on arc takes place. The rated current contacts are in this way advantageously protected against damage caused by an arc.
The power breaker has at least one piston-cylinder arrangement which moves such that it is coupled to the rated current contacts and in which a portion of the insulating medium which fills the arcing chamber is pressurized in a compression volume by a piston during disconnection. The pressurized insulating medium produced in this way, which is frequently SF6 gas, is used to assist the process of blowing out the arc, as a result of which the disconnection capacity of the power breaker is advantageously improved, in particular for small disconnection currents as well.
It has been found to be particularly advantageous that, in this power breaker, at least a portion of the kinetic energy which the rated current contacts have toward the end of their disconnection travel can be used with the aid of the drive linkage for acceleration of the contact pin and for the movement of a pressure piston connected to the contact pin. If this advantage is made use of, the drive can be designed to be considerably weaker, which also has an advantageous effect on the price.